Alaska Airlines and American Airlines, once strong partners in codeshare and loyalty, are further distancing their relationship. Starting on March 1, 2020, it will no longer be possible to redeem AAdvantage miles to book flights on Alaska nor will it be possible to spend Mileage Plan miles to book on American.

The changes comes amid ongoing, eroding relations between the two carriers. Alaska and American in 2017 took away the ability for frequent flyers to earn miles on each other’s flights (though it was and still remains possible to earn miles on codeshares). With limitations now around the way that Alaska and American mileage partners can spend miles, the programs are even further out of sync.

Much has changed at Alaska in the last few years to help precipitate these changes. After the Seattle-based company successfully completed the acquisition of its West Coast rival Virgin America in 2016, the combined carrier had greater reach and a stronger route network for travelers to leverage — easing the need for partner flights.

Alaska has also scaled up its loyalty program in other sectors, easing its reliance on legacy American carriers. The airline, for example, launched a new partnership with El Al, the flag carrier of Israel, in May.

American, for its part, paints the looming erosion as good for its frequent flyers, suggesting that more seats will now be available for AAdvantage frequent flyers. In an e-mailed statement, the carrier said that “AAdvantage members rely on American for their award travel, and we’re committed to providing a network that gets them where they want to go. We routinely review our airline partners and programs with that focus in mind, and we are making changes to our partnership with Alaska Airlines as a result.”

Indeed, both AAdvantage and Mileage Plan members may find slightly more award seats on their home carrier available after March 1 when the ability to book partner flights goes away. But the lack of a partner on which to book unique flights — particularly for American passengers looking to book out of Seattle or Alaska passengers leaning on American’s strong Latin America network — will surely sting.

Grant Martin [gm@skift.com] curates the Skift Business of Loyalty newsletter. He is also a director of product marketing at TripActions. Skift emails the newsletter every Monday.

Photo Credit: An Alaska Airlines agent interacts with a customer. Bloomberg